Display device including photo pixel with improved sensing sensitivity

ABSTRACT

A display device includes a substrate, a driving layer which is disposed on the substrate, and includes first driving circuit groups each including N first pixel driving circuits and photo pixels each including a photo driving circuit and a photo sensor electrically connected to the photo driving circuit. A display element layer is on the driving layer, and includes first display element groups each including N first display elements electrically connected to the respective N first pixel driving circuits. Minimum distances between first color display elements included in the first display elements in a first predetermined direction in a plan view, are substantially the same. A distance between two first pixel driving circuits adjacent to each other in a second predetermined direction with the photo pixel therebetween in the plan view is different from a distance between two first pixel driving circuits continuously disposed in the second predetermined direction.

This application claims priority to Korean Patent Application No.10-2017-0099204, filed on Aug. 4, 2017, and all the benefits accruingtherefrom under 35 U.S.C. § 119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND 1. Field

Exemplary embodiments of the invention relate to a display device, andmore particularly to a display device including a light sensing area.

2. Description of the Related Art

Recently, display devices have a function for sensing user'sfingerprints. Examples of a fingerprint recognition method include anelectrostatic capacity type based on a change in capacitance of acapacitor formed between electrodes, an optical type using an opticalsensor, and an ultrasonic type using a piezoelectric body.

SUMMARY

In an optical type using an optical sensor, a separate modular opticalsensor is disposed (e.g., mounted) in a display device, so that itraises costs while sensitivity does not reach a level at which afingerprint of a user is sensed.

Exemplary embodiments of the invention provide a display deviceincluding a photo pixel with improved sensing sensitivity built in adriving layer of a display panel.

Exemplary embodiments of the invention also provide a display devicethat does not change the arrangement structure of display elements evenwhen photo pixel areas are provided in a light sensing area and thusmaintains a constant resolution in a display area regardless of thearea.

An exemplary embodiment of the invention provides a display deviceincludes a substrate, a driving layer, and a display element layer. Thedriving layer is disposed on the substrate, and includes first drivingcircuit groups each including N first pixel driving circuits and photopixels. N is a natural number and each of the photo pixels includes aphoto driving circuit and a photo sensor electrically connected to thephoto driving circuit. The display element layer is disposed on thedriving layer, and includes first display element groups each includingN first display elements electrically connected to the respective Nfirst pixel driving circuits. Minimum distances between first colordisplay elements included in the N first display elements, which aremeasured in a first predetermined direction in a plan view, aresubstantially the same. A distance between two first pixel drivingcircuits of the N first pixel driving circuits adjacent to each other ina second predetermined direction with a photo pixel of the photo pixelstherebetween in the plan view is different from a distance between twofirst pixel driving circuits of the N first pixel driving circuitscontinuously disposed in the second predetermined direction.

In an exemplary embodiment, the each driving layer may further includesecond driving circuit groups including N second pixel driving circuits,where the each display element layer may further include N seconddisplay elements electrically connected to the N second pixel drivingcircuits, where minimum distances between first color display elementsincluded in the N second display elements, which are measured in thefirst predetermined direction in the plan view, may be substantially thesame, where distances between adjacent two second pixel driving circuitsof the N second pixel driving circuits, which are measured in the secondpredetermined direction in the plan view, may be substantially the same.

In an exemplary embodiment, a display area where an image may bedisplayed and a non-display area adjacent to the display area aredefined on the display device, where the display area may include anormal display area and a light sensing area which senses a user's inputby an incident light, where the first driving circuit groups and thefirst display element groups may be disposed in the light sensing areain the plan view, where the second driving circuit groups and the seconddisplay element groups may be disposed in the normal display area in theplan view.

In an exemplary embodiment, an area that each of the first drivingcircuit groups and each of the second driving circuit groups occupiesmay be substantially the same, where an area that each of the firstdisplay element groups and each of the second display element groupsoccupies may be substantially the same.

In an exemplary embodiment, an area that each of the N first pixeldriving circuits may be smaller than an area that each of the N secondpixel driving circuits occupies.

In an exemplary embodiment, a first driving circuit group among thefirst driving circuit groups and a second driving circuit group amongthe second driving circuit groups adjacent to the first driving circuitgroup in a first direction may be spaced apart from each other to definea vacant area.

In an exemplary embodiment, a distance between a first pixel drivingcircuit of the first driving circuit group adjacent to each other in thefirst direction and a second pixel driving circuit of the second drivingcircuit group may be greater than a distance between two first pixeldriving circuits of the N first pixel driving circuits included in therespective first driving circuit groups and adjacent to each other inthe first direction and a distance between two second pixel drivingcircuits of the N second pixel driving circuits included in therespective second driving circuit groups and adjacent to each other inthe first direction.

In an exemplary embodiment, the driving layer may further include signallines, where a predetermined number of the signal lines may have a bentshape in the vacant area.

In an exemplary embodiment, a predetermined number of the signal linesmay be branched in the vacant area to be electrically connected to the Nfirst pixel driving circuits and the photo driving circuit.

In an exemplary embodiment, the photo sensor may include a lower metallayer disposed on the substrate, an active layer disposed on the lowermetal layer, an upper metal layer which is disposed on the active layerand in which an opening exposing a portion of the active layer isdefined, an absorption filter which is disposed on the upper metal layerand covers the opening, and an interference filter which is disposed onthe upper metal layer and covers the opening.

In an exemplary embodiment, the display element layer may include apixel definition film which overlaps the photo sensor, and a lens whichoverlaps the photo sensor on the pixel definition film and includes thesame material as that of the pixel definition film.

In an exemplary embodiment, a display area where an image is displayedand a non-display area adjacent to the display area may be defined onthe display device, where the non-display area may include a firstbending area defined outside a first side of the display area in a firstdirection, a first pad area defined outside the first bending area inthe first direction, a second bending area defined outside a second sideof the display area in the first direction, and a second pad areadefined outside the second bending area in the first direction, wherethe substrate may be bent along a bending axis extending in a seconddirection intersecting the first direction in the first and secondbending areas. The display device may further include a first drivingcircuit chip which provides a signal to the N first pixel drivingcircuits and the photo driving circuit and is disposed on the first padarea, and a second driving circuit chip which receives a signal sensedby the photo pixel and is disposed in the second pad area.

In an exemplary embodiment, the display device may further include aflexible printed circuit substrate which connects the first pad area andthe second pad area of the display device to each other.

In an exemplary embodiment of the invention, a display device mayinclude a substrate, a driving layer disposed on the substrate, andincluding first driving circuit groups each including a plurality offirst pixel driving circuits and photo pixels and second driving circuitgroups each including a plurality of second pixel driving circuits, anda display element layer disposed on the driving layer, and including aplurality of display elements electrically connected to the plurality offirst pixel driving circuits and the plurality of second pixel drivingcircuits, where minimum distances between first color display elementsincluded in the plurality of display elements, which are measured in afirst predetermined direction in the plan view, are substantially thesame, where a first driving circuit group among the first drivingcircuit groups and a second driving circuit group among the seconddriving circuit groups adjacent to the first driving circuit group in afirst direction are spaced apart from each other.

In an exemplary embodiment, a distance between a first pixel drivingcircuit of the first driving circuit group adjacent to each other in thefirst direction and a second pixel driving circuit of the second drivingcircuit group may be greater than a distance between two first pixeldriving circuits of the plurality of first pixel driving circuitsincluded in the respective first driving circuit groups and adjacent toeach other in the first direction and a distance between two secondpixel driving circuits of the plurality of second pixel driving circuitsincluded in the respective second driving circuit groups and adjacent toeach other in the first direction.

In an exemplary embodiment of the invention, a display device includes afirst scanning line which receives a first scanning signal, a secondscanning line which receives a second scanning signal different from thefirst scanning signal, a sensing line which is insulated from the firstand second scanning lines, a display element which receives the firstand second scanning lines from the first and second scanning signals andemit light, and a photo pixel which receives the first and secondscanning signals from the first and second scanning lines and provide acurrent to the sensing line based on a light reflected by a user amongthe light emitted from the display element.

In an exemplary embodiment, the photo pixel may include a photo sensorincluding a cathode and an anode which receive a power voltage, a firsttransistor including a gate terminal connected to the second scanningline, a first terminal connected to the anode of the photo sensor, and asecond terminal connected to the sensing line, and a second transistorincluding a gate terminal connected to the first scanning line, a firstterminal which receives an initialization voltage lower than the powervoltage, and a second terminal connected to the anode of the photosensor.

In an exemplary embodiment, the photo pixel may include a photo sensorincluding a cathode and an anode which receive a power voltage, a firsttransistor including a gate terminal connected to the second scanningline, a first terminal, and a second terminal connected to the sensingline, a second transistor including a gate terminal connected to thefirst scanning line, a first terminal which receives an initializationvoltage lower than the power voltage, and a second terminal connected tothe anode of the photo sensor, and a third transistor including a gateterminal connected to the anode of the photo sensor, a first terminalwhich receives the power voltage, and a second terminal connected to thefirst terminal of the first transistor.

In an exemplary embodiment, the photo pixel may include a photo sensorincluding an anode and a cathode which receive an initializationvoltage, a first transistor including a gate terminal connected to thesecond scanning line, a first e terminal connected to the cathode of thephoto sensor, and a second terminal connected to the sensing line, and asecond transistor including a gate terminal connected to the firstscanning line, a first terminal which receives a power voltage higherthan the initialization voltage, and a second terminal connected to thecathode of the photo sensor.

In an exemplary embodiment, the photo pixel may include a photo sensorincluding an anode and a cathode which receive an initializationvoltage, a first transistor including a gate terminal connected to thesecond scanning line, a first terminal, and a second terminal connectedto the sensing line, a second transistor including a gate terminalconnected to the first scanning line, a first terminal which receives apower voltage higher than the initialization voltage, and a secondterminal connected to the cathode of the photo sensor, and a thirdtransistor including a gate terminal connected to the cathode of thephoto sensor, a first terminal which receives the power voltage, and asecond terminal connected to the first terminal of the first transistor.

In an exemplary embodiment, the photo pixel may include a photo sensorincluding an anode and a cathode which receive an initializationvoltage, a first transistor including a gate terminal connected to thecathode of the photo sensor, a first terminal, and a second terminal, asecond transistor including a gate terminal connected to the secondscanning line, a first terminal connected to the second terminal of thefirst transistor, and a second terminal connected to the sensing line, athird transistor including a gate terminal connected to the firstscanning line, a first terminal connected to the cathode of the photosensor, and a second terminal connected to the first terminal of thefirst transistor, a fourth transistor including a gate terminalconnected to the first scanning line, a first terminal which receives apower voltage higher than the initialization voltage, and a secondterminal connected to the first terminal of the second transistor, and afifth transistor including a gate terminal connected to the secondscanning line, a first terminal which receives the power voltage, and asecond terminal connected to the first terminal of the first transistor.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate exemplaryembodiments of the invention and, together with the description, serveto explain principles of the invention. In the drawings:

FIG. 1 is a perspective view of an exemplary embodiment of a displaydevice according to the invention;

FIG. 2 is a plan view of a display device of FIG. 1;

FIG. 3 is a side view of a display device of FIG. 1;

FIG. 4 is a cross-sectional view showing an exemplary embodiment of adisplay panel according to the invention;

FIG. 5 is a plan view showing an exemplary embodiment of a driving layerand a display element layer of a display panel according to theinvention shown in FIG. 2;

FIG. 6 is a view showing a display element layer in FIG. 5;

FIG. 7 is a view showing a driving layer in FIG. 5;

FIG. 8A is a conceptual diagram showing one pixel driving circuit of afirst unit driving circuit shown in FIG. 7, and FIG. 8B is a conceptualdiagram of one pixel driving circuit of a second unit driving circuitshown in FIG. 7;

FIG. 9 is a view showing a driving layer including signal lines in FIG.5;

FIG. 10 is a cross-sectional view of a display panel taken along lineI-I′ in FIG. 5;

FIG. 11 is a view showing a cross-sectional structure of anotherexemplary embodiment of a display panel according to the invention;

FIG. 12 is a block diagram showing one pixel, and FIG. 13 is one blockdiagram showing a photo sensor;

FIG. 14 is a circuit diagram showing one pixel of FIG. 12;

FIGS. 15 to 19 are circuit diagrams showing exemplary embodiments of onephoto pixel of FIG. 13 according to the invention; and

FIG. 20 is a waveform diagram of a signal applied to FIG. 19, and

FIGS. 21A to 21C are diagrams for explaining a driving mechanism of aphoto pixel for each section.

DETAILED DESCRIPTION

Hereinafter, another exemplary embodiment of the invention will bedescribed with reference to the drawings. In this specification, when itis mentioned that a component (or, an area, a layer, a part, etc.) isreferred to as being “on”, “connected to” or “combined to” anothercomponent, this means that the component may be directly on, connectedto, or combined to the other component or a third component therebetweenmay be present.

Like reference numerals refer to like elements. Additionally, in thedrawings, the thicknesses, proportions, and dimensions of components areexaggerated for effective description. “And/or” includes all of one ormore combinations defined by related components.

It will be understood that the terms “first” and “second” are usedherein to describe various components but these components should not belimited by these terms. The above terms are used only to distinguish onecomponent from another. For example, a first component may be referredto as a second component and vice versa without departing from the scopeof the invention. The singular expressions include plural expressionsunless the context clearly dictates otherwise.

In addition, terms such as “below”, “the lower side”, “on”, and “theupper side” are used to describe a relationship of configurations shownin the drawing. The terms are described as a relative concept based on adirection shown in the drawing.

In various embodiments of the invention, the term “include,” “comprise,”“including,” or “comprising,” specifies a property, a region, a fixednumber, a step, a process, an element and/or a component but does notexclude other properties, regions, fixed numbers, steps, processes,elements and/or components.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and theinvention, and will not be interpreted in an idealized or overly formalsense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. In an exemplary embodiment, a region illustrated ordescribed as flat may, typically, have rough and/or nonlinear features.Moreover, sharp angles that are illustrated may be rounded. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the precise shape of a region andare not intended to limit the scope of the claims.

FIG. 1 is a perspective view of a display device according to anexemplary embodiment of the invention.

Referring to FIG. 1, a display area DA1 where an image is displayed anda non-display area NDA1 adjacent to the display area DA1 are defined ona display surface IS of a display device 1000. A plurality of pixels PX(refer to FIG. 2) may be disposed in the display area DA1. Thenon-display area NDA1 is an area where no image is displayed. Thedisplay surface IS of the display device 1000 may be the outermostsurface of the display device 1000 and may be a surface that a userviews. FIG. 1 exemplarily shows that the display area DA1 has arectangular form and the non-display area NDA surrounds the display areaDA1. However, the invention is not limited thereto, and the display areaDA1 and the non-display area NDA1 may have various shapes.

As shown in FIG. 1, the display surface IS where the image IM isdisplayed is parallel to the plane defined by a first direction DR1 anda second direction DR2. The normal direction of the display surface IS,that is, a thickness direction of the display device DD, indicates athird direction DR3. The front surface (or an upper surface) and therear surface (or a lower surface) of each member may be defined by thethird direction DR3. However, the directions that the first to thirddirections DR1, DR2, and DR3 indicate may be converted to otherdirections as a relative concept.

The display device 1000 may sense the user's touch inputted to thedisplay area DA1. The display device 1000 may include a touch panelcapable of sensing the user's touch inputted to the display area DA1.

A light sensing area FPA may be further defined on the display surfaceIS of the display device 1000. The display device 1000 may sense thelight inputted to the light sensing area FPA to sense the user's input.The light sensing area FPA may measure the heart rate by sensing theminute movement of the user's fingerprint or the user's finger. Thedisplay device 1000 may include a photo pixel HX (refer to FIG. 2)disposed in the light sensing area FPA. Details will be described later.

FIG. 1 exemplarily shows that the light sensing area FPA is defined inthe display area DA1. However, the invention is not limited thereto. Inan exemplary embodiment, the light sensing area FPA may be defined inthe non-display area NDA1 and may be defined to overlap both the displayarea DA1 and the non-display area NDA1, for example.

FIG. 2 is a plan view of the display device of FIG. 1, and FIG. 3 is aside view of the display device of FIG. 1.

Referring to FIGS. 2 and 3, the display device 1000 may include adisplay panel DP, a first driving circuit chip DIC, a second drivingcircuit chip PIC, and a flexible printed circuit substrate FPC.

The display panel DP may be a light-emitting display panel, and is notparticularly limited. In an exemplary embodiment, the display panel DPmay be an organic light emitting display panel or a quantum dot lightemitting display panel, for example. In the organic light emittingdisplay panel, the emission layer includes an organic light emittingmaterial. In relation to the quantum dot light emitting display panel,an emission layer includes quantum dots and quantum rods. Hereinafter,the display panel DP is described as an organic light emitting displaypanel.

The display panel DP may include a display area DA and a non-displayarea NDA adjacent to the display area DA in the plan view. The displaypanel DP may display an image in the display area DA and may not displayan image in the non-display area NDA. The display area DA and thenon-display area NDA shown in FIG. 2 correspond to the display area DA1and the non-display area NDA1 shown in FIG. 1, respectively. However,the display area DA and the non-display area NDA of the display panel DPmay not be necessarily identical to the display area DA1 and thenon-display area NDA1 of the display device 1000, and may vary accordingto a structure/design of the display panel DP.

The display area DA may include a light sensing area FPA and a normaldisplay area RDA spaced apart from the light sensing area FPA. The lightsensing area FPA and the normal display area RDA may have differentcircuit structures. Details will be described later.

The non-display area NDA may include a first bending area BA1, a secondbending area BA2, and a first pad area PDA1, and a second pad area PDA2.

The first bending area BA1 is defined as an area across the displaypanel DP in a second direction DR2 and outside the one side of thedisplay area DA in a first direction DR1 in the plan view. The first padarea PDA1 is defined outside the first bending area BA1 in the firstdirection DR1 in the plan view. The display panel DP may be bent along afirst bending axis BX1 extending in the second direction DR2 within thefirst bending area BA1. As the first bending area BA1 is bent from theupper surface DP1 of the display panel DP to the direction of the lowersurface DP2 (a direction opposite to the third direction DR3), the firstpad area PDA1 of the display panel DP is disposed below the display areaDA.

The second bending area BA2 may be an area across the display panel DPin the second direction DR2 outside the other side of the display areaDA which is opposite to the one side of the display area DA in the firstdirection DR1 in the plan view. The second pad area PDA2 is definedoutside the second bending area BA2 in the first direction DR1 in theplan view. The display panel DP may be bent along a second bending axisBX2 extending in the second direction DR2 within the second bending areaBA2. As the second bending area BA2 is bent from the upper surface DP1of the display panel DP to the direction of the lower surface DP2 (adirection opposite to the third direction DR3), the second pad area PDA2of the display panel DP is disposed below the display area DA.

The display panel DP may include a pixel PX, a photo pixel HX, aplurality of signal lines, and a scanning driving circuit GDC.

The pixel PX is disposed in the display area DA to display an image. Thephoto pixel HX may be disposed in the light sensing area FPA and receivethe reflected light by a user to sense the user's input.

The signal lines may include a scanning line SL, a data line DL, a powerline PL, and a sensing line RX. A plurality of scanning lines SL, aplurality of data lines DL, and a plurality of power lines PL areprovided, but respective ones of the signals are illustrated in FIG. 2for convenience.

The scanning line SL, the data line DL, and the power line PL areconnected to the pixel PX. The data line DL and the power line PL may beconnected to the first driving circuit chip DIC to receive a drivingsignal.

The photo pixel FIX may be connected to the sensing line RX. The photopixel FIX may be connected to the scanning line SL and the power line PLto which the corresponding pixel is connected. Details will be describedlater. The sensing line RX may be connected to the second drivingcircuit chip PIC.

The scanning driving circuit GDC may be disposed in the non-display areaNDA. The scanning driving circuit GDC may generate a scanning signal andoutput the generated scanning signal to the scanning line SL.

In an exemplary embodiment, the scanning driving circuit GDC may includea plurality of thin film transistors (“TFTs”) provided through the sameprocess as the driving circuit of the pixels PX, for example, a lowtemperature polycrystalline silicon (“LTPS”) process or a lowtemperature polycrystalline oxide (“LTPO”) process, for example.However, the invention is not limited thereto, and the plurality of TFTsmay be provided by various other processes.

The first driving circuit chip DIC may be disposed in the first pad areaPDA1. The first driving circuit chip DIC may be directly disposed (e.g.,mounted) on the first pad area PDA1 but is not limited thereto, and maybe disposed (e.g., mounted) on a flexible printed circuit substrate (notshown) connected to the first pad area PDA1. The first driving circuitchip DIC provides a signal necessary for driving the display panel DP.That is, the first driving circuit chip DIC may provide a signal to thedata line DL and the power line PL. The first driving circuit chip DICmay be a source driver integrated circuit that provides a data signal tothe data line DL.

The second driving circuit chip PIC may be disposed in the second padarea PDA2. The second driving circuit chip PIC may be directly disposed(e.g., mounted) on the second pad area PDA2 but is not limited thereto,and may be disposed (e.g., mounted) on a flexible printed circuitsubstrate (not shown) connected to the second pad area PDA2. The seconddriving circuit chip PIC may receive the signal sensed by the photopixel HX through the sensing line RX and sense the user's input based onthe received signal.

The light sensing area FPA may be defined to be closer to the other endDA22 of the display area DA, which is relatively closer to the seconddriving circuit chip PIC, than to the one end DA11 in the firstdirection DR1. Accordingly, the second driving circuit chip PIC isarranged in the second pad area PDA2 adjacent to the other end DA22 ofthe display area DA and this is advantageous to reduce the resistancevalue of the sensing line RX and improve the sensitivity of the photopixel HX.

In an exemplary embodiment of the invention, even when the first andsecond driving circuit chips DIC and PIC are disposed in the first andsecond pad areas PDA1 and PDA2, respectively, since the first and secondbending areas BA1 and BA2 are bent and both ends of the display panel DPwhich are opposite to each other in the first direction DR1 are bentdownward, the area occupied by the non-display area (“NDA”) in the planview may be reduced.

The flexible printed circuit substrate FPC is connected to the first padarea PDA1 and the second pad area PDA2 of the display panel DP toprovide a path through which the first and second driving circuit chipsDIC and PIC exchange signals. Although FIGS. 2 and 3 exemplarily showthat the flexible printed circuit substrate FPC is directly connected tothe first pad area PDA1 and the second pad area PDA2, the invention isnot limited thereto, and the flexible printed circuit substrate FPC maybe connected to the first pad area PDA1 or the second pad area PDA2through another flexible printed circuit substrate.

The second driving circuit chip PIC may receive a timing signal, avoltage signal, and so on desired for driving the photo pixel FIXthrough the flexible printed circuit substrate FPC and output thesensing result through the sensing line RX.

The second driving circuit chip PIC may be electrically connected to atleast one of the data line DL and the power line PL. FIG. 2 exemplarilyshows that the second driving circuit chip PIC is electrically connectedto the power line PL. The second driving circuit chip PIC may receive asignal to be applied to the power line PL through the flexible printedcircuit substrate FPC and may apply a signal necessary for the powerline PL in addition to the first driving circuit chip DIC. Since thedisplay panel DP is implemented in a large area, the length of wirespassing through the display area DA may become long, and the brightnessdrop due to a RC delay difference may occur in the display area DA. Itis possible to improve a difference in brightness that may occur at theboth ends of the display area DA along the first direction DR1 as eachof the first and second driving circuit chips DIC and PIC applies thesame signal to the both ends of one of signal lines.

Although not shown in the drawing, in an exemplary embodiment, theflexible printed circuit substrate FPC may include a force driving chip.In the exemplary embodiment, the display panel may further include aforce sensor disposed in the light sensing area FPA. The force drivingchip may measure the intensity of the user's input applied to the lightsensing area FPA based on the signal outputted from the force sensor.

FIG. 4 is a cross-sectional view showing a display panel according to anexemplary embodiment of the invention.

The display panel DP may include a substrate 100, a driving layer 200, adisplay element layer 300, and a sealing layer 400. Although not shownseparately, the display panel DP may further include a protective memberdisposed below the substrate 100 and a window member disposed on thesealing layer 400. Further, the display panel DP may further includefunctional layers such as an antireflection layer, a refractive indexcontrol layer, and so on.

The substrate 100 may include at least one plastic film. The substrate100 may include a flexible substrate, such as a plastic substrate, aglass substrate, a metal substrate, or an organic/inorganic compositesubstrate. The display area DA and the non-display area NDA describedwith reference to FIGS. 2 and 3 may be equally defined on the substrate100.

The driving layer 200 is disposed on the substrate 100. The drivinglayer 200 includes at least one intermediate insulation layer and acircuit element. The intermediate insulation layer includes at least oneintermediate inorganic film and at least one intermediate organic film.The circuit element includes the signal lines, the scanning drivingcircuit GDC, the pixel driving circuit of the pixel PX, the photo sensorof the photo pixel, and the photo driving circuit of the photo pixel,which are described with reference to FIG. 2. Detailed description forthis will be made later.

The display element layer 300 is disposed on the driving layer 200. Thedisplay element layer 300 includes a display element. In an exemplaryembodiment of the invention, the display element may be an organic lightemitting diode. The display element layer 300 may further include anorganic layer such as a pixel definition film.

The sealing layer 400 seals the display element layer 300. The sealinglayer 400 includes at least one inorganic film (hereinafter referred toas a sealing inorganic film). The sealing layer 400 may further includeat least one organic film (hereinafter referred to as a sealing organicfilm). The sealing inorganic film protects the display element layer 300from moisture/oxygen, and the sealing organic film protects the displayelement layer 300 from foreign substances such as dust particles. In anexemplary embodiment, the sealing organic layer may include a siliconnitride layer, a silicon oxynitride layer, and a silicon oxide layer, atitanium oxide layer, or an aluminum oxide layer, for example. In anexemplary embodiment, the sealing organic layer may include anacryl-based organic layer, for example, but is not limited thereto.

The display panel DP may further include a touch sensing unit TSdisposed on the sealing layer 400. The touch sensing unit TS obtainscoordinate information of an external input. The touch sensing unit TSmay be disposed directly on the sealing layer 400. In thisspecification, “directly disposed” means “being formed” through acontinuous process, excluding “attached” through an additional adhesivelayer. However, the invention is not limited thereto, and the touchsensing unit TS may be attached to the sealing layer 400 through anadhesive as a separate independent module.

The touch sensing unit TS may have a multi-layer structure. The touchsensing unit TS may include a single layer or a multilayer conductivelayer. The touch sensing unit TS may include a single layer or amultilayer insulation layer.

The touch sensing unit TS, for example, may sense an external input in acapacitive manner. In the invention, an operating method of the touchsensing unit TS is not limited especially and according to an exemplaryembodiment of the invention, the touch sensing unit TS may sense anexternal input through an electromagnetic induction method or a pressuredetection method.

FIG. 5 is a plan view showing a driving layer and a display elementlayer of a display panel according to an exemplary embodiment of theinvention shown in FIG. 2. FIG. 6 is a view showing a display elementlayer in FIG. 5. FIG. 7 is a view showing a driving layer in FIG. 5.FIGS. 5 to 7 are enlarged views of a partial area AA of a display panelDP shown in FIG. 2.

Hereinafter, a distance between display elements means a distancebetween the centers of the respective display elements.

Referring to FIGS. 4 to 6, the display element layer 300 may includefirst display element groups UP1 and UP2 disposed in a light sensingarea FPA and second display element groups UP3 and UP4 disposed in anormal display area RDA.

Each of the first display element groups UP1 and UP2 may be the minimumdisplay elements repeatedly arranged in the light sensing area FPA. InFIG. 6, the same two first display elements UP1 and UP2 are shown, andthis is described below based on one first display element group UP1.

The first display element group UP1 may include N display elements OD. Nmay be a natural number and may be set variously. The display elementsdisposed in the first display element group UP1 may be defined as firstdisplay elements. In the exemplary embodiment of the invention, thefirst display element group UP1 includes two red display elements XR1and XR2, two blue display elements XB1 and XB2, and four green displayelements XG1 to XG4. The green display elements XG1 to XG4 have smallerareas than those of the red display elements XR1 and XR2 and the bluedisplay elements XB1 and XB2, respectively, and the number of greendisplay elements XG1 to XG4 is greater than the number of red displayelements XR1 and XR2 and is greater than the number of blue displayelements XB1 and XB2. In an exemplary embodiment of the invention,because the human eye has a relatively high perceived resolution togreen compared to red and blue, the number of green display elements XG1to XG4 may be provided relatively greater than that of the red displayelements XR1 and XR2 and that of the blue display elements XB1 and XB2to improve green resolution.

However, the invention is not limited thereto, and the number of displayelements included in the first display element group UP1, the colorratio of display elements, and the like may be variously adjusted.

Photo pixel areas HA1 to HA4 may be defined in the display element layer300. The photo pixel areas HA1 and HA2 may be areas where photo sensorsPD1 to PD4 (refer to FIG. 7) are disposed.

The photo pixel areas HA1 to HA4 may be defined between the displayelements OD in the plan view. In FIG. 6, when taking one photo pixelarea HA1 as an example, the photo pixel area HA1 may be defined in anarea surrounded by the red display element XR2, the blue display elementXB1, and the two adjacent green display elements XG4 and XG7. The numberand positions of the photo pixel areas HA1 to HA4 may be variouslydefined.

Each of the second display element groups UP3 and UP4 may be the minimumdisplay elements repeatedly arranged in the normal display area RDA. InFIG. 6, the same two second display elements UP3 and UP4 are shown, andthis is described below based on one second display element group UP3.

The second display element group UP3 may include N display elements OD.The second display element group UP3 may have substantially the samestructure as that of the first display element group UP1. The displayelements disposed in the second display element group UP3 may be definedas second display elements. In the exemplary embodiment of theinvention, the second display element group UP3 includes two red displayelements XR5 and XR6, two blue display elements XB5 and XB6, and fourgreen display elements XG9 to XG12. A photo pixel area is not definedbetween the display elements OD of the second display element group UP3.

The first display element group UP1 and the second display element groupUP3 have the same arrangement structure of the display elements OD. Thatis, the minimum distances between predetermined color display elementsadjacent to each other in a predetermined direction or a directionorthogonal to the predetermined direction may be substantially all thesame.

In an exemplary embodiment, the distance DT1 between the two red displayelements XR3 and XR4 of the first display element group UP2 in the fifthdirection DR5 may be substantially identical to the distance DT2 betweenthe red display elements XR3 of the first display element group UP2 andthe red display element XR8 of the second display element group UP4 inthe fourth direction DR4 orthogonal to the fifth direction DR5, forexample. In the same manner, the distance DT3 between the two greendisplay elements XG1 and XG2 of the first display element group UP1 inthe second direction DR2 may be substantially identical to the distanceDT4 between the green display elements XG1 of the first display elementgroup UP1 and the green display element XG11 of the second displayelement group UP3 in the first direction DR1 orthogonal to the seconddirection DR2.

According to an exemplary embodiment of the invention, even when thephoto pixel areas HA1 to HA4 are provided in the light sensing area FPA,the arrangement structure of the display elements is not changed, sothat the display device may keep the resolution within the display areaconstant regardless of the area.

FIG. 8A is a conceptual diagram showing one pixel driving circuit of afirst unit driving circuit shown in FIG. 7, and FIG. 8B is a conceptualdiagram of one pixel driving circuit of a second unit driving circuitshown in FIG. 7.

Hereinafter, the distance between the pixel driving circuits means thedistance between the centers of the areas occupied by each of the pixeldriving circuits.

Referring to FIGS. 4, 5, 7, 8 a and 8 b, the driving layer 200 mayinclude the first driving circuit groups UC1 and UC2 disposed in thelight sensing area FPA, and the second driving circuit groups UC3 andUC4 disposed in the normal display area RDA.

Each of the first driving circuit groups UC1 and UC2 may be a minimumunit circuit that is repeatedly arranged in the light sensing area FPA.In FIG. 7, the same two first driving circuit groups UC1 and UC2 areshown, and this is described below based on the first driving circuitgroup UC1 for convenience.

The first driving circuit group UC1 includes circuits for driving thefirst display element group UP1 (refer to FIG. 6) and photo pixels HX1and HX2. One first driving circuit group UC1 includes N pixel drivingcircuits CK1 to CK8. The photo pixels HX1 and HX2 may respectivelyinclude photo driving circuits PK1 and PK2 and photo sensors PD1 andPD2.

N may be a natural number, and the number of pixel driving circuits CK1to CK8 may be changed according to the arrangement structure of thepixel PX provided in the first display element group UP1. In anexemplary embodiment of the invention, since the display elements PXhave a structure in which eight display elements (e.g., two red displayelements, two blue display elements, and four green display elements)are repeatedly arranged, the number of pixel driving circuits CK1 to CK8may also be eight, for example.

The pixel driving circuits CK1 to CK8 of the first driving circuit groupUC1 may include transistors and capacitors for driving the correspondingdisplay element OD of the first display element group UP1. Predeterminedcircuits of the pixel driving circuits CK1 to CK8 are described below.

The photo sensors PD1 and PD2 are disposed to overlap with the photopixel areas HA1 and HA2 shown in FIG. 6. The number and positions of thephoto pixel areas HA1 and HA2 of FIG. 6 are determined by the number andpositions of the photo pixels HX1 and HX2.

The photo driving circuits PK1 and PK2 may include transistors andcapacitors for driving the photo sensors PD1 and PD2. Predeterminedcircuits of the pixel driving circuits PK1 and PK2 are described below.

Each of the second driving circuit groups UC3 and UC4 may be a minimumunit circuit that is repeatedly arranged in the normal display area RDA.In FIG. 7, the same two second driving circuit groups UC3 and UC4 areshown, and this is described below based on the second driving circuitgroup UC3 for convenience.

The second driving circuit group UC3 includes circuits for driving thesecond display element group UP3 (refer to FIG. 6). The second drivingcircuit group UC3 may include N pixel driving circuits CK17 to CK24. Thepixel driving circuits CK17 to CK24 of the second driving circuit groupUC3 may include transistors and a capacitor for driving thecorresponding display elements of the second display element group UP3.

The areas occupied by the first driving circuit group UC1 and the seconddriving circuit group UC3 may be substantially equal to each other. Thenumber of pixel driving circuits disposed in each of the first drivingcircuit group UC1 and the second driving circuit group UC3 is the sameand the photo driving circuits PK1 and PK2 are further disposed in thefirst driving circuit group UC1. Therefore, the area occupied by thepixel driving circuits CK1 to CK8 of the first driving circuit group UC1may be smaller than the area occupied by the pixel driving circuits CK17to CK24 of the second driving circuit group UC3. In an exemplaryembodiment, the area occupied by each of the pixel driving circuits CK1to CK8 in the first driving circuit group UC1 may be the same with oneanother, and the area occupied by each of the pixel driving circuitsCK17 to CK24 in the second driving circuit group UC3 may be the samewith one another. However, the invention is not limited thereto.

According to an exemplary embodiment of the invention, the width DT5 ofthe area occupied by one pixel driving circuit CK1 of the first drivingcircuit group UC1 in the second direction DR2 may be less than the widthDT6 of the area occupied by one pixel driving circuit CK21 of the seconddriving circuit group UC3 in the second direction DR2. The width DT7 ofthe area occupied by one pixel driving circuit CK1 of the first drivingcircuit group UC1 in the first direction DR1 may be identical to thewidth DT8 of the area occupied by one pixel driving circuit CK21 of thesecond driving circuit group UC3 in the first direction DR1. However,the invention is not limited thereto. When the area occupied by thepixel driving circuit CK1 of the first driving circuit group UC1 issmaller than the area occupied by the pixel driving circuit CK21 of thesecond driving circuit group UC3, the shape of the pixel driving circuitCK1 of the first driving circuit group UC1 may be changed variously.

The distance between two pixel driving circuits that are adjacent toeach other in a predetermined direction with the photo pixels HX1 andHX2 therebetween may be different from the distance between two pixeldriving circuits arranged continuously in a predetermined direction. Inan exemplary embodiment, the photo pixel HX1 is disposed between thepixel driving circuit CK4 of the first driving circuit group UC1 and thepixel driving circuit CK9 of the first driving circuit group UC2 in thesecond direction DR2, for example. The pixel driving circuits CK3 andCK4 of the first driving circuit group UC1 are continuously arranged inthe second direction DR2. The distance DT9 between the pixel drivingcircuits CK4 and CK9 in the second direction DR2 may be greater than thedistance DT10 between the pixel driving circuits CK3 and CK4 in thesecond direction DR2.

The pixel driving circuits CK1 to CK8 of the first driving circuit groupUC1 are connected to the corresponding display elements XG1 to XG4, XR1,XR2, XB1, and XB2 of the first display element group UP1 through firstcontact holes CH1. In addition, the pixel driving circuits CK17 to CK24of the second driving circuit group UC3 are connected to thecorresponding display elements XG9 to XG12, XR5, XR6, XB5, and XB6 ofthe second display element group UP3 through second contact holes CH2.The distance DT11 between the first contact holes CH1 in the seconddirection DR2 may be smaller than the distance DT12 between the secondcontact holes CH2 in the second direction DR2. Although the distancebetween the first contact holes CH1 becomes smaller than the distancebetween the second contact holes CH2, it is not affected that the pixeldriving circuits CK1 to CK8 of the first driving circuit group UC1 andthe display elements XG1 to XG4, XR1, XR2, XB1 and XB2 of the firstdisplay element group UP1 are connected. That is, although the displayelements of the first and second display element groups UP1 to UP4 areregularly disposed, the position of the first contact hole CH1 may bepartially changed.

The distance between the first contact holes CH1 in the first directionDR1 and the distance between the second contact holes CH2 in the firstdirection DR1 and the distance between the first contact holes CH1 andthe second contact hole CH2 in the first direction DR1 may be the same.

The first driving circuit group UC1 and the second driving circuit groupUC3 may be spaced apart in the first direction DR1. An area between thefirst driving circuit group UC1 and the second driving circuit group UC3in the first direction DR1 may be defined as a vacant area VA. The pixeldriving circuits CK1 to CK32 or the photo pixels HX1 to HX4 are notdisposed in the vacant area VA of the driving layer 200. The vacant areaVA may be defined to traverse the display area DA (refer to FIG. 2) ofthe display panel DP along the second direction DR2.

The pixel driving circuit CK1 of the first driving circuit group UC1 andthe pixel driving circuit CK21 of the second driving circuit group UC3may have an inverted shape with respect to an axis extending in thesecond direction DR2. By changing the position of the first contact holeCH1 in the pixel driving circuit CK1 of the first driving circuit groupUC1 and the position of the second contact hole CH2 in the pixel drivingcircuit CK21 of the second driving circuit group UC3, it is possible tosecure the vacant area VA while maintaining the distance between thefirst contact hole CH1 and the second contact hole CH2 in the firstdirection DR1.

The distance DT13 between the pixel driving circuit CK1 of the firstdriving circuit group UC1 and the pixel driving circuit CK21 of thesecond driving circuit group UC3, which are adjacent to each other inthe first direction DR1, is greater than the distance DT14 between twopixel driving circuits CK1 and CK5, which are included in the respectivefirst driving circuit groups UC1 and adjacent to each other in the firstdirection DR1 and the distance DT15 between the two second pixel drivingcircuits CK17 and CK21, which are included in the respective seconddriving circuit groups UC3 and adjacent to each other in the firstdirection DR1.

Referring to FIGS. 8A and 8B, the pixel driving circuit CK21 of thesecond driving circuit group UC3 and the pixel driving circuit CK1 ofthe first driving circuit group UC1 corresponding thereto are shown. Itis shown that a portion CKP1 of a circuit disposed in the pixel drivingcircuit CK21 has an “L” shape in the plan view. It is shown that aportion CKP2 of a circuit disposed in the pixel driving circuit CK1 hasan inversed “L” shape. However, since the width DT5 of the pixel drivingcircuit CK1 in the second direction DR2 is smaller than the width DT6 ofthe pixel driving circuit CK21, the width of the portion CKP2 of thecircuit disposed in the pixel driving circuit CK1 in the first directionDR1 is smaller than the width of the portion CKP1 of the circuitdisposed in the pixel driving circuit CK21.

FIG. 9 is a view showing a driving layer including signal lines in FIG.5. FIG. 9 is an enlarged view of a partial area AA of a display panel DPshown in FIG. 2.

Referring to FIGS. 4, 5, 7 and 9, the signal lines of the driving layer200 include scanning lines SL1 to SL4, data lines DL1 to DL8, powerlines PL1 to PL8, initialization lines IL1 to IL4, light-emission linesML1 to ML4, and sensing lines RX1 and RX2. The predetermined function ofeach signal line will be described later.

The transistors and the capacitors provided in each of the pixel drivingcircuits CK1 to CK32 may be connected to at least one of the scanninglines SL1 to SL4, at least one of the data lines DL1 to DL8, at leastone of the power lines PL1 to PL8, at least one of the initializationlines IL1 to IL4, and at least one of the light-emission lines ML1 toML4.

The transistors and the capacitors included in each of the photo drivingcircuits PK1 to PK4 may be connected to at least one of the sensinglines RX1 and RX2.

In an exemplary embodiment of the invention, the widths of the pixeldriving circuits CK1 to CK16 disposed in the first driving circuitgroups UC1 and UC2 in the second direction DR2 and the widths of thepixel driving circuit CK17 to CK32 disposed in the second drivingcircuit groups UC3 and UC4 are different. Therefore, alternatively, thesignal lines, for example, the power lines PL1 to PL8 and data lines DL1to DL8, extending along the first direction DR1 may have a partiallybent shape in a vacant area VA between the first driving circuit groupsUC1 and UC2 and the second driving circuit groups UC3 and UC4

When it is assumed that there is no vacant area VA, for example, thepower line PL2 extends in the first direction DR1 until it passes thesecond driving circuit group UC3, is bent drastically in the seconddirection DR2 immediately after passing the second driving circuit groupUC3, and then is bent again in the first direction DR1 and passes thefirst driving circuit group UC1. However, this type of wiring structureis not easy to be designed and consequently degrades the displayquality.

In an exemplary embodiment of the invention, by securing the vacant areaVA, some of the signal lines between the first and second drivingcircuit groups UC1 and UC3 may easily change the extending direction.

Also, some of the signal lines, for example, the power lines PL4 andPL8, may be connected to the transistors of the photo driving circuitsPK1 to PK4. When description is made based on the fourth power line PL4,for example, the power line PL4 may be branched in the vacant area VAand provided to the pixel driving circuits CK3 and CK7 and the photodriving circuit PK1 to PK2 of the first driving circuit group UC1.

The driving layer 200 may further include dummy scanning lines SLd1 andSLd2. The dummy scanning lines SLd1 and SLd2 may be connected to thepixel driving circuit of the second driving circuit group UC2 to providea signal for initializing the pixel driving circuit of the seconddriving circuit group UC2. The dummy scanning lines SLd1 and SLd2 may bedisposed in the vacant area VA.

FIG. 10 is a cross-sectional view of a display panel taken along lineI-I′ in FIG. 5.

Referring to FIGS. 7 and 10, the photo driving circuit PK1 to PK4 of thedriving layer 200 may include phototransistors. The photo drivingcircuit PK1 to PK4 may include a plurality of photo transistors, but onephoto transistor TRP connected to the photo sensor PD is illustrativelyshown in FIG. 10.

The pixel driving circuits CK1 to CK32 of the driving layer 200 mayinclude pixel transistors and one pixel transistor TRX connected to thefirst electrode EL1 of the display element OD is illustratively shown inFIG. 10.

A buffer layer 201 for blocking the penetration of impurities may bedisposed on the substrate 100. In an exemplary embodiment, the bufferlayer 201 may include an inorganic material such as silicon oxide,silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride,titanium oxide, or titanium nitride, or may include an organic materialsuch as polyimide, polyester, or acrylic, or may include a stack of aplurality of materials selected from the above-listed materials.

The photo transistor TRP of the photo driving circuit PK includes anactive layer 211, a gate electrode 213, a source electrode 215, and adrain electrode 217.

The active layer 211 may be disposed on the buffer layer 201. Thedriving layer 200 may further include a first insulation layer 221disposed between the active layer 211 and the gate electrode 213. Thefirst insulation layer 221 may insulate the active layer 211 from thegate electrode 213. The source electrode 215 and the drain electrode 217may be disposed on the gate electrode 213. The driving layer 200 mayfurther include a second insulation layer 223 disposed between the gateelectrode 213 and the source electrode 215 and between the gateelectrode 213 and the drain electrode 217. The source electrode 215 andthe drain electrode 217 may be connected to the active layer 211 throughthe contact holes CT1 provided in the first insulation layer 221 and thesecond insulation layer 223, respectively.

The structure of the photo transistor TRP is not limited to thestructure shown in FIG. 10, and the positions of the active layer 211,the gate electrode 213, the source electrode 215, and the drainelectrode 217 may be modified in various forms. In another exemplaryembodiment, in FIG. 10, the gate electrode 213 may be disposed below theactive layer 211, for example.

The photo sensor PD may include a lower metal layer 240, an upper metallayer 250, a first active layer 231, a second active layer 235, and athird active layer 233.

The lower metal layer 240 may include a metallic material. The lowermetal layer 240 may block light incident on the first to third activelayers 231, 233, and 235. The lower metal layer 240 may be connected tothe drain electrode 217 of the photo transistor TRP. The lower metallayer 240 may be an anode or a cathode.

The upper metal layer 250 may cover the edges of the photo sensor PD toblock light incident on the edges of the first to third active layers231, 233, and 235. An opening OP exposing a portion of the second activelayer 235 may be defined in the upper metal layer 250 in correspondenceto the central portions of the first to third active layers 231, 233,and 235 to provide a path through which light is incident on the firstto third active layers 231, 233, and 235. The upper metal layer 250 maybe a cathode when the first electrode 231 is an anode, or an anode whenthe first electrode 231 is a cathode. The upper metal layer 250 may beconnected to any one of the signal lines to receive a signal providedfrom the connected signal line.

The lower metal layer 240 and the upper metal layer 250 again reflectslight, which is not absorbed by the first to third active layers 231,233, and 235, and reflected, to the inside to increase the lightabsorption rate of the first to third active layers 231, 233, and 235.Accordingly, the sensing sensitivity of the photo sensor PD may beimproved by the lower metal layer 240 and the upper metal layer 250.

The first active layer 231 may be disposed on the lower metal layer 240and may contact the lower metal layer 240.

The second active layer 235 may be disposed below the upper metal layer250 and may contact the upper metal layer 250. The second active layer235 may be connected to the upper metal layer 250 through a contact holedefined in the second insulation layer 223.

The third active layer 233 is disposed between the first active layer231 and the second active layer 235. The third active layer 233 may bean intrinsic semiconductor.

Depending on which one of an anode and a cathode each of the lower metallayer 240 and the upper metal layer 250 functions as, the first activelayer 231 and the second active layer 235 may be a P-type semiconductoror an N-type semiconductor in order and vice versa. The third activelayer 233 may be an intrinsic semiconductor.

When light is incident on the photo sensor PD, holes and electrons aregenerated in the third active layer 233, and a current is generated bythe movement thereof. The photo driving circuit PK senses the currentflowing to the lower metal layer 240 of the photo sensor PD to sense theuser's input applied to the photo pixel area HA. The light source of thephoto sensor PD for sensing the user's input may be a display element ODadjacent to the photo sensor PD. A part of the light emitted from thedisplay element OD may be reflected by the user's finger or the likeoverlapping with the photo pixel area HA and then, may be incident onthe photo sensor PD.

The photo sensor PD may further include an absorption filter 260 and aninterference filter 270.

The absorption filter 260 is disposed on the upper metal layer 250 andcovers the opening OP provided in the upper metal layer 250. Theabsorption filter 260 may selectively absorb light of a predeterminedwavelength. The transmission band of the absorption filter 260 mayoverlap the light-emission band of the display element OLD. Theabsorption filter 260 may improve the sensitivity of the photo sensor PDby removing noise due to external light except for the display elementOLD.

The interference filter 270 may be disposed on the absorption filter260. The interference filter 270 may selectively transmit light incidentat a predetermined range of angles. Various angles of light may beincident on the photo sensor PD, and the resolution of a user inputdecreases as the angle of the incident light is varied. The photo sensorPD more precisely sense a user's input by receiving only a limited rangeof angles through the interference filter 270.

The positions of the absorption filter 260 and the interference filter270 may be changed with each other, and at least one filter may beomitted in other exemplary embodiments.

The pixel transistor TRX includes an active layer 281, a gate electrode283, a source electrode 285, and a drain electrode 287.

In an exemplary embodiment of the invention, the active layer 281, gateelectrode 283, source electrode 285, and drain electrode 287 of thepixel transistor TRX are substantially the same as the respectivecomponents of the photo transistor TRP. Therefore, detailed descriptionthereof will be omitted. However, the invention is not limited thereto,and the positions of the respective components of the pixel transistorTRX and the photo transistor TRP may be different from each other.

The driving layer 200 may further include a third insulation layer 225.The third insulation layer 225 may be disposed on the source electrode215 and the drain electrode 217 of the photo transistor TRP and may bedisposed on the source electrode 285 and the drain electrode 287 of thepixel transistor TRX. The third insulation layer 225 may be disposed onthe absorption filter 260 and the interference filter 270.

The display element layer 300 may include a display element OD and apixel definition film PDL.

The pixel definition film PDL is disposed on the third insulation layer225. The pixel definition film PDL may be disposed to overlap the photosensor PD.

The pixel definition film PDL may be disposed to partially overlap thefirst electrode EL1 of the display element OD.

The display element OD may be an organic light-emitting element. Thedisplay element OD may include a first electrode ELL an organic layerOL, and a second electrode EL2.

The first electrode EL1 is disposed on the third insulation layer 225.The first electrode EL1 is connected to the drain electrode 287 of thepixel transistor TRX through a contact hole CT2 defined in the thirdinsulation layer 225.

The first electrode EL1 may be a pixel electrode or an anode. The firstelectrode EL1 may be a transmissive electrode, a semi-transmissiveelectrode, or a reflective electrode. In an exemplary embodiment, whenthe first electrode EL1 is a transmissive electrode, the first electrodeEL1 may include a transparent metal oxide such as indium tin oxide(“ITO”), indium zinc oxide (“IZO”), zinc oxide (ZnO), and indium tinzinc oxide (“ITZO”), for example. In an exemplary embodiment, when thefirst electrode EL1 is a semi-transmissive electrode or a reflectiveelectrode, the first electrode EL1 may include a combination of Ag, Mg,Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a metal, for example.

The first electrode EL1 may be a single layer or a multilayer structurehaving a plurality of layers including a transparent metal oxide ormetal. In an exemplary embodiment, the first electrode EL1 may be asingle layer structure of ITO, Ag, or a metal combination (e.g., acombination of Ag and Mg), a two-layer structure of ITO/Mg or ITO/MgF,or a three-layer structure of ITO/Ag/ITO, for example, but is notlimited thereto.

The organic layer OL may include an organic emission layer (“EML”)including a low-molecular organic material or a polymer organicmaterial. The organic light emission layer may emit light. In anexemplary embodiment, the organic emission layer OD may selectivelyfurther include a hole transport layer (“HTL”), a hole injection layer(“HIL”), an electron transport layer (“ETL”), and an electron injectionlayer (“EIL”) in addition to the organic emission layer, for example.

The second electrode EL2 may be provided on the organic layer OL. Thesecond electrode EL2 may be a common electrode or a cathode. The secondelectrode EL2 may be a transmissive electrode, a semi-transmissiveelectrode, or a reflective electrode. In an exemplary embodiment, whenthe second electrode EL2 is a transmissive electrode, the secondelectrode EL2 may include Li, Liq, Ca, LiF/Ca, LiF/Al, Al, Mg, BaF, or acombination thereof (e.g., a combination of Ag and Mg).

In an exemplary embodiment, when the second electrode EL2 is asemi-transmissive electrode or a reflective electrode, the secondelectrode EL2 may include Ag, Liq, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr,Li, Ca, LiF/Ca, LiF/Al, Mo, Ti, or a combination thereof (e.g., acombination of Ag and Mg). In an alternative exemplary embodiment, thesecond electrode EL2 may have a multilayer structure including areflective layer or a semi-transmissive layer including the material,and a transparent conductive layer including ITO, IZO, zinc oxide (ZnO),and ITZO, for example.

The second electrode EL2 may include an auxiliary electrode. In anexemplary embodiment, the auxiliary electrode may include a filmprovided by depositing the material toward the light emission layer, anda transparent metal oxide on the film such as ITO, IZO, zinc oxide(ZnO), and ITZO, and may include Mo, Ti, Ag, or the like, for example.

When the display element OD is a front light-emission, the firstelectrode EL1 may be a reflective electrode and the second electrode EL2may be a transmissive electrode or a semi-transmissive electrode. Whenthe display element OD is a back light-emitting element, the firstelectrode EL1 may be a transmissive electrode or a semi-transmissiveelectrode, and the second electrode EL2 may be a reflective electrode.

The display element layer 300 may further include a lens LZ. The lens LZmay be disposed in the photo pixel area HA and may be disposed tooverlap the photo sensor PD. The lens LZ may be disposed on a pixeldefinition film PDL. The lens LZ may include the same material as thatof the pixel definition film PDL, and may be provided in the sameoperation. In particular, the lens LZ may be provided using a multi-tonemask when forming the pixel definition film PDL in the photo pixel areaHA. Therefore, the lens LZ may include the same material as that of thepixel definition film PDL.

The lens LZ is not disposed on the pixel definition film PDL between thedisplay elements OLD disposed in the normal display area RDA. The lensLZ functions as a convex lens and focuses light, which is reflected by auser and incident on the lens LZ among lights emitted from the displayelement OLD, to the photo sensor PD. Therefore, the sensing sensitivityof the photo sensor PD may be improved by the lens LZ.

The sealing layer 400 may be disposed on the second electrode EL2.

FIG. 11 is a view showing a cross-sectional structure of a display panelaccording to another exemplary embodiment of the invention.

A display panel DP-1 shown in FIG. 11 is substantially similar to thedisplay DP shown in FIG. 10 except that it further includes a controllayer 280 as compared with the display panel DP described with referenceto FIG. 10.

Hereinafter, substantially the same components among the components ofFIGS. 10 and 11 are denoted by the same reference numerals, and thecontrol layer 280 will be mainly described.

The driving layer 200 may further include the control layer 280.

The control layer 280 may be disposed below a lower metal layer 240. Thecontrol layer 280 may be disposed in the same layer as the active layer211 of the photo transistor TRP.

The control layer 280 may block the light incident on the first to thirdactive layers 231, 233 and 235 together with the lower metal layer 240to improve the sensing sensitivity of the photo sensor PD′.Additionally, the control layer 280 also increases the position of thephoto sensor PD in the third direction DR3, that is, the thicknessdirection of the display panel DP-1, so that an optical path throughwhich the light reflected by a user reaches the photo sensor PD may beshortened and as a result, the sensing sensitivity of the photo sensorPD′ may be improved. In addition, since the control layer 280 and thelower metal layer 240 form a capacitor and the capacitor is used in aphoto driving circuit, the space for forming a capacitor on the planarsurface may be omitted, so that it may improve the degree of freedom ofcircuit design of a photo driving circuit.

In FIG. 11, the control layer 280 is shown as one. However, in anotherexemplary embodiment, a plurality of control layers may be providedusing a layer below the lower metal layer 240.

FIG. 12 is a block diagram showing one pixel, and FIG. 13 is one blockdiagram showing a photo sensor.

Referring to FIGS. 10 and 12, in an exemplary embodiment of theinvention, the pixel PX may include a pixel driving circuit included inthe driving layer 200 of the display panel DP, and a display element ODelectrically connected to the pixel driving circuit and included in thedisplay element layer 300.

The pixel PX receives a power voltage ELVDD, a scanning signal Sn, adata signal Dm, an initialization voltage Vint, and an emission controlsignal En and emits light from the display element OD.

Referring to FIGS. 10 and 13, in an exemplary embodiment of theinvention, the photo pixel HX may include a photo driving circuitincluded in the driving layer 200 of the display panel DP, and a photosensor PD electrically connected to the photo driving circuit.

Referring to FIG. 13, the photo pixel HX receives the power voltageELVDD, the scanning signal Sn, the initialization voltage Vint, andlight reflected by a user and outputs a sensing signal Rn sensed by aphoto sensor.

The photo pixel HX may receive the power voltage ELVDD, the scanningsignal Sn, and the initialization voltage Vint applied to thecorresponding pixel PX. The photo pixel HX shares the signal line withthe pixel PX and outputs the sensing signal Rn using the signal appliedto the pixel PX to simplify the design of the photo driving circuit.

FIG. 14 is a circuit diagram showing one pixel of FIG. 12.

One pixel PX according to an exemplary embodiment of the invention mayinclude a plurality of transistors T1 to T7, a storage capacitor Cst,and an organic emission element OLED.

The TFTs T1 to T7 include a driving transistor T1, a switchingtransistor T2, a compensation transistor T3, an initializationtransistor T4, a first emission control transistor T5, a second emissioncontrol transistor T6, and a bypass transistor T7.

The pixel PX is connected to a first scanning line 14 for transmittingthe nth scanning signal Sn to the switching transistor T2 and thecompensation transistor T3, a second scanning line 24 for transmittingthe n−1th scanning signal Sn−1 to the initialization transistor T4, athird scanning line 34 for transmitting the n+1th scanning signal Sn+1to the bypass transistor T7, a light-emission line 15 for transmittingan emission control signal En to the first emission control transistorT5 and the second emission control transistor T6, a data line 16 fortransmitting the data signal Dm, a power line 26 for transmitting thepower supply voltage ELVDD, and an initialization line 22 fortransmitting the initialization voltage Vint for initializing thedriving transistor T1.

The gate electrode G1 of the driving transistor T1 is connected to thefirst electrode C1 of the storage capacitor Cst. The source electrode S1of the driving transistor T1 is connected to the power line 26 throughthe first emission control transistor T5. The drain electrode D1 of thedriving transistor T1 is electrically connected to the anode of theorganic emission element OLED through the second emission controltransistor T6. The driving transistor T1 receives the data signal Dmaccording to the switching operation of the switching transistor T2 andsupplies the driving current Id to the organic emission element OLED.

The gate electrode G2 of the switching transistor T2 is connected to thefirst scanning line 14. The source electrode S2 of the switchingtransistor T2 is connected to the data line 16. The drain electrode D2of the switching transistor T2 is connected to the source electrode S1of the driving transistor T1 and is connected to the power line 26through the first emission control transistor T5. The switchingtransistor T2 performs a switching operation that is turned on accordingto the first scanning signal Sn received through the first scanning line14 and supplies the data signal Dm received through the data line 16 tothe source electrode S1 of the driving transistor T1.

The gate electrode G3 of the compensation transistor T3 is connected tothe first scanning line 14. The source electrode S3 of the compensationtransistor T3 is connected to the drain electrode D1 of the drivingtransistor T1 and is connected to the anode of the organic emissionelement OLED through the second emission control transistor T6 (refer toa first node NP1). The drain electrode D3 of the compensation transistorT3 is connected to the first electrode C1 of the storage capacitor Cst,the source electrode S4 of the initialization transistor T4, and thegate electrode G1 of the driving transistor T1 (refer to a second nodeNP2). The compensation transistor T3 is turned on according to the nthscanning signal Sn received through the first scanning line 14 toconnect the gate electrode G1 and the drain electrode D1 of the drivingtransistor T1 to each other in order for the diode connection of thedriving transistor T1.

The gate electrode G4 of the initialization transistor T4 is connectedto the second scanning line 24. The drain electrode D4 of theinitialization transistor T4 is connected to the initialization line 22.The source electrode S4 of the initialization transistor T4 is connectedto the first electrode C1 of the storage capacitor Cst, the drainelectrode D3 of the compensation transistor T3, and the gate electrodeG1 of the driving transistor T1. The initialization transistor T4 isturned on according to the n−1th scanning signal Sn−1 received throughthe second scanning line 24 and delivers the initialization voltage Vintto the gate electrode G1 of the driving transistor T1 to initialize thevoltage of the gate electrode G1 of the driving transistor T1.

The gate electrode G5 of the first emission control transistor T5 isconnected to the light-emission line 15. The first emission controltransistor T5 may be connected between the power line 26 and the drivingtransistor T1. The source electrode S5 of the first emission controltransistor T5 is connected to the power line 26. The drain electrode D5of the first emission control transistor T5 is connected to the sourceelectrode S1 of the driving transistor T1 and the drain electrode D2 ofthe switching transistor T2. As the emission control signal En isapplied to the gate electrode G5 of the first emission controltransistor T5, the first emission control transistor T5 is turned on sothat the driving current Id flows in the organic emission element OLED.The first emission control transistor T5 may determine the timing atwhich the driving current Id flows into the organic emission elementOLED.

The gate electrode G6 of the second emission control transistor T6 isconnected to the light-emission line 15. The second emission controltransistor T6 may be connected between the driving transistor T1 and theorganic emission element OLED. The source electrode S6 of the secondemission control transistor T6 is connected to the drain electrode D1 ofthe driving transistor T1 and the source electrode S3 of thecompensation transistor T3. The drain electrode D6 of the secondemission control transistor T6 is electrically connected to the anode ofthe organic emission element OLED. The first emission control transistorT5 and the second emission control transistor T6 are turned on accordingto the emission control signal En received through the light emissionline 15. As the emission control signal En is applied to the gateelectrode G6 of the second emission control transistor T6, the secondemission control transistor T6 is turned on so that the driving currentId flows in the organic emission element OLED. The second emissioncontrol transistor T6 may determine the timing at which the drivingcurrent Id flows into the organic emission element OLED.

The gate electrode G7 of the bypass transistor T7 is connected to thethird scanning line 34. The source electrode S7 of the bypass transistorT7 is connected to the anode of the organic emission element OLED. Thedrain electrode D7 of the bypass transistor T7 is connected to theinitialization line 22. The bypass transistor T7 is turned on accordingto the n+1th scanning signal Sn+1 received through the third scanningline 34 to initialize the anode of the organic emission element OLED.

The second electrode C2 of the storage capacitor Cst is connected to thepower line 26. The first electrode C1 of the storage capacitor Cst isconnected to the gate electrode G1 of the driving transistor T1, thedrain electrode D3 of the compensation transistor T3, and the sourceelectrode S4 of the initialization transistor T4.

The cathode of the organic emission element OLED receives the referencevoltage ELVSS. The organic emission element OLED receives the drivingcurrent Id from the driving transistor T1 and emits light.

In another exemplary embodiment of the invention, the number andconnections of the transistors T1 to T7 constituting the pixel PX may bevariously changed.

FIG. 15 is a circuit diagram showing one photo pixel of FIG. 13according to an exemplary embodiment of the invention.

A photo pixel HX-1 according to an exemplary embodiment of the inventionmay include photo transistors T11 and T21, a photo capacitor Cant, and aphoto sensor PD-1.

The photo transistors T11 and T21 may include a first transistor T11 anda second transistor T21. In an exemplary embodiment of the invention, itis exemplarily shown that each of the first and second transistors T11and T21 is a p-type transistor. However, the invention is not limitedthereto.

The photo pixel HX-1 includes a first scanning line 44 for transmittingthe n+1th scanning signal Sn+1, a second scanning line 54 fortransmitting the nth scanning signal Sn, and a sensing line 64.

The gate terminal of the first transistor T11 is connected to the secondscanning line 54. One terminal of the first transistor T11 is connectedto the anode of the photo sensor PD-1 and the other terminal isconnected to the sensing line 64.

The gate terminal of the second transistor T21 is connected to the firstscanning line 44 and one terminal receives the initialization voltageVint and the other terminal is connected to the anode of the photosensor PD-1.

In the exemplary embodiment of FIG. 15, the lower metal layer of thephoto sensor PD-1 may be an anode and the upper metal layer may be acathode. The cathode of the photo sensor PD-1 receives a power voltageELVDD. One electrode and the other electrode of the photo-capacitor Cap1are connected to the anode and the cathode of the photo sensor PD-1,respectively.

The first node N1 connected to the anode of the photo sensor PD-1 may beinitialized to the initialization voltage Vint before the frame in whichthe photo sensor PD-1 is driven.

When light is not applied to the photo sensor PD-1, the first node N1maintains the initialization voltage Vint and the photo capacitor Cap1charges the charge corresponding to the voltage difference between thepower voltage ELVDD and the initialization voltage Vint.

Then, when light is applied to the photo sensor PD-1, as the voltage ofthe first node N1 approaches the power voltage ELVDD, the chargescharged in the photo-capacitor Cap1 are discharged.

When the nth scanning signal Sn is applied to the second scanning line54 and the first transistor T11 is turned on, a current flows to thesensing line 64 by the charge discharged from the photo capacitor Capt.

Then, when the first transistor T11 is turned off and the n+1th scanningsignal Sn+1 is applied and the second transistor T21 is turned on, theanode of the photo sensor PD-1 is initialized by the initializationvoltage Vint.

FIG. 16 is a circuit diagram showing one photo pixel of FIG. 13according to an exemplary embodiment of the invention.

The photo pixel shown in FIG. 16 differs from the photo pixel describedwith reference to FIG. 15 in the third transistor, and therefore, thethird transistor will be mainly described.

The photo pixel HX-2 may further include a third transistor T31. In anexemplary embodiment of the invention, it is exemplarily shown that thethird transistor T31 is a p-type transistor. However, the invention isnot limited thereto.

The gate terminal of the third transistor T31 is connected to the anodeof the photo sensor PD-1. One terminal may receive the power voltageELVDD, and the other terminal may be connected to one terminal of thefirst transistor T11.

The third transistor T31 may increase the amount of a current flowing inthe sensing line 64 by amplifying the voltage change of the voltage ofthe first node N1 as light is applied to the photo sensor PD-1.

FIG. 17 is a circuit diagram showing one photo pixel of FIG. 13according to another exemplary embodiment of the invention.

A photo pixel HX-3 shown in FIG. 17 may include photo transistors T12and T22, a photo capacitor Cap2, and a photo sensor PD-2.

The photo transistors T12 and T22 may include a first transistor T12 anda second transistor T22. In an exemplary embodiment of the invention, itis exemplarily shown that each of the first and second transistors T12and T22 is a p-type transistor. However, the invention is not limitedthereto.

The photo pixel HX-3 includes a first scanning line 44 for transmittingthe n+1th scanning signal Sn+1, a second scanning line 54 fortransmitting the nth scanning signal Sn, and a sensing line 64.

The gate terminal of the first transistor T12 is connected to the secondscanning line 54. One terminal of the first transistor T12 is connectedto the cathode of the photo sensor PD-2 and the other terminal isconnected to the sensing line 64.

The gate terminal of the second transistor T22 is connected to the firstscanning line 44 and one terminal receives the power voltage ELVDD andthe other terminal is connected to the cathode of the photo sensor PD-2.

In the exemplary embodiment of FIG. 17, the lower metal layer of thephoto sensor PD-2 may be a cathode and the upper metal layer may be ananode. The anode of the photo sensor PD-2 receives the initializationvoltage Vint. One electrode and the other electrode of the photocapacitor Cap2 are connected to the anode and the cathode of the photosensor PD-2, respectively.

The second node N2 connected to the cathode of the photo sensor PD-2 ischarged with the power voltage ELVDD before the frame in which the photosensor PD-1 is driven.

When light is not applied to the photo sensor PD-2, the second node N2maintains the power voltage ELVDD and the photo capacitor Cap2 chargesthe charge corresponding to the voltage difference between the powervoltage ELVDD and the initialization voltage Vint.

Then, when light is applied to the photo sensor PD-2, the voltage of thesecond node N2 approaches the initialization voltage Vint.

When the nth scanning signal Sn is applied to the second scanning line54 and the first transistor T12 is turned on, a current flows to thesensing line 64 by the voltage of the second node N2. When light isincident on the photo sensor PD-2, the amount of a current flowing tothe sensing line 64 may be reduced.

Then, when the first transistor T12 is turned off and the n+1th scanningsignal Sn+1 is applied and the second transistor T22 is turned on, thecathode of the photo sensor PD-2 is charged with the power voltageELVDD.

FIG. 18 is a circuit diagram showing one photo pixel of FIG. 13according to another exemplary embodiment of the invention.

The photo pixel shown in FIG. 18 differs from the photo pixel describedwith reference to FIG. 17 in the third transistor, and therefore, thethird transistor will be mainly described.

The photo pixel HX-4 may further include a third transistor T32. In anexemplary embodiment of the invention, it is exemplarily shown that thethird transistor T32 is a p-type transistor. However, the invention isnot limited thereto.

The gate terminal of the third transistor T32 is connected to thecathode of the photo sensor PD-2. One terminal may receive the powervoltage ELVDD, and the other terminal may be connected to one terminalof the first transistor T12.

The third transistor T32 may increase the amount of a current flowing inthe sensing line 64 by amplifying the voltage change of the voltage ofthe second node N2 as light is applied to the photo sensor PD-2.

FIG. 19 is a circuit diagram showing one photo pixel of FIG. 13according to another exemplary embodiment of the invention.

A photo pixel HX-5 shown in FIG. 19 includes photo transistors T13, T23,T33, T43, and T53, a first photo capacitor Cap3, a second photocapacitor Cap4 and a photo sensor PD-3.

The photo transistor may include first to fifth transistors T13, T23,T33, T43, and T53. In an exemplary embodiment of the invention, it isexemplarily shown that each of the first and fifth transistors T13, T23,T33, T43, and T53 is a p-type transistor. However, the invention is notlimited thereto.

The photo pixel HX-5 includes a first scanning line 44 for transmittingthe n+1th scanning signal Sn+1, a second scanning line 54 fortransmitting the nth scanning signal Sn, and a sensing line 64.

The gate terminal of the first transistor T13 is connected to thecathode of the photo sensor PD-3. One terminal of the first transistorT13 is connected to the other terminal of the fifth transistor T53 andthe other terminal of the first transistor T13 is connected to oneterminal of the second transistor T23.

The gate terminal of the second transistor T23 is connected to thesecond scanning line 54. One terminal of the second transistor T23 isconnected to the other terminal of the first transistor T13 and theother terminal of the second transistor T23 is connected to the sensingline 64.

The gate terminal of the third transistor T33 is connected to the firstscanning line 44. One terminal of the third transistor T33 is connectedto one electrode of the second photo capacitor Cap4 and the cathode ofthe photo sensor PD-5, and the other terminal is connected to oneterminal of the first transistor T13.

The gate terminal of the fourth transistor T43 is connected to the firstscanning line 44 and one terminal receives the power voltage ELVDD andthe other terminal is connected to the one terminal of the secondtransistor T23.

The gate terminal of the fifth transistor T53 is connected to the secondscanning line 54 and one terminal receives the power voltage ELVDD andthe other terminal is connected to the one terminal of the firsttransistor T13.

One electrode of the second photo cathode Cap4 is connected to the firstscanning line 44 and the other electrode is connected to the cathode ofthe photo sensor PD-3.

One electrode and the other electrode of the first photo capacitor Cap3are connected to the anode and the cathode of the photo sensor PD-3,respectively.

FIG. 20 is a waveform diagram of a signal applied to FIG. 19, and FIGS.21A to 21C are diagrams for explaining a driving mechanism of a photopixel for each section.

Referring to FIGS. 20 and 21A, the second transistor T23 and the fifthtransistor T53 are turned on during the first section PR1 in which thenth scanning signal Sn is activated.

If light is applied to the photo sensor PD-3 before the first sectionPR1, the gate voltage of the first transistor T13 is lowered by thephoto sensor PD-3, and as the first transistor T13 operates, a currentRn flows through the sensing line 64 during the first section PR1.

Referring to FIGS. 20 and 21B, the third transistor T33 and the fourthtransistor T43 are turned on during the second section PR2 in which then+1th scanning signal Sn+1 is activated. The power voltage ELVDD istransmitted to the gate terminal of the first transistor T13 through apath that sequentially passes through the fourth transistor T43, thefirst transistor T13, and the third transistor T33, and the firsttransistor T13 is turned off as the gate terminal voltage of thetransistor T13 increases. As the first transistor T13 is turned offduring the second section PR2, the voltage for compensating thethreshold voltage of the first transistor T13 is stored in the gateterminal of the first transistor T13.

Referring to FIGS. 20 and 21C, the photo sensor PD-3 receives lightduring the third section PR3 until the nth scanning signal Sn isactivated again. When light is applied to the photo sensor PD-3 duringthe third period PR3, the voltage of the gate terminal of the firsttransistor T13 becomes close to the initialization voltage Vint.

According to an exemplary embodiment of the invention, by adding theoperation of compensating the threshold voltage of the first transistorT13 using signals (the nth scanning signal and the n+1th scanningsignal) for driving the pixels, the non-uniformity issue of sensingsensitivity due to the threshold voltage dispersion of the transistorT13 may be solved.

In a display device according to an exemplary embodiment of theinvention, the display device has a photo pixel built in a driving layerof a display panel to improve sensing sensitivity.

According to a display device according to an exemplary embodiment ofthe invention, even though photo pixel areas are provided in a lightsensing area, the arrangement structure of display elements may not bechanged. Therefore, the display device may maintain the resolutionwithin the display area constant regardless of the area.

Although the exemplary embodiments of the invention have been described,it is understood that the invention should not be limited to theseexemplary embodiments but various changes and modifications may be madeby one ordinary skilled in the art within the spirit and scope of theinvention as hereinafter claimed.

What is claimed is:
 1. A display device comprising: a substrate; adriving layer disposed on the substrate, and comprising: first drivingcircuit groups each comprising N first pixel driving circuits and photopixels, and second driving circuit groups each comprising N second pixeldriving circuits spaced apart from the first driving circuit groups in afirst direction, wherein N is a natural number and each of the photopixels comprises a photo driving circuit and a photo sensor electricallyconnected to the photo driving circuit; and a display element layerdisposed on the driving layer, and comprising first display elementgroups each comprising N first display elements electrically connectedto the respective N first pixel driving circuits through N first contactholes, respectively, and second display element groups each comprising Nsecond display elements electrically connected to the N second pixeldriving circuits through N second contact holes, wherein a minimumdistance measured in a first predetermined direction between first colordisplay elements included in the plurality of first display elements ina plan view and a minimum distance measured in a second predetermineddirection orthogonal to the first predetermined direction between firstcolor display elements included in the plurality of first displayelements in the plan view are substantially the same, wherein a distancebetween two first pixel driving circuits of the N first pixel drivingcircuits adjacent to each other in a second direction which is identicalto or different from the first predetermined direction and differentfrom the first direction with a photo pixel of the photo pixelstherebetween in the plan view is different from a distance between twofirst pixel driving circuits of the N first pixel driving circuitscontinuously disposed in the second direction, and wherein a distancebetween first contact holes of the N first contact holes respectivelycorresponding to directly adjacent first pixel driving circuits of the Nfirst pixel driving circuits is smaller than a distance between adjacentsecond contact holes of the N second contact holes respectivelycorresponding to directly adjacent second pixel driving circuits of theN second pixel driving circuits, in the second direction.
 2. The displaydevice of claim 1, wherein minimum distances between first color displayelements included in the plurality of second display elements, which aremeasured in the first predetermined direction in the plan view, aresubstantially the same, wherein distances between adjacent two secondpixel driving circuits of the N second pixel driving circuits, which aremeasured in the first direction in the plan view, are substantially thesame.
 3. The display device of claim 2, wherein a display area where animage is displayed and a non-display area adjacent to the display areaare defined on the display device, wherein the display area comprises anormal display area and a light sensing area for sensing a user's inputby an incident light, wherein the first driving circuit groups and thefirst display element groups are disposed in the light sensing area inthe plan view, wherein the second driving circuit groups and the seconddisplay element groups are disposed in the normal display area in theplan view.
 4. The display device of claim 3, wherein an area which eachof the first driving circuit groups occupies and an area which each ofthe second driving circuit groups occupies are substantially the same,wherein an area which each of the first display element groups occupiesand an area which each of the second display element groups occupies aresubstantially the same.
 5. The display device of claim 3, wherein anarea which each of the N first pixel driving circuits is smaller than anarea which each of the N second pixel driving circuits occupies.
 6. Thedisplay device of claim 3, wherein a first driving circuit group amongthe first driving circuit groups and a second driving circuit groupamong the second driving circuit groups adjacent to the first drivingcircuit group in a second direction crossing the first direction arespaced apart from each other to define a vacant area.
 7. The displaydevice of claim 6, wherein a distance between a first pixel drivingcircuit of the first driving circuit group in the second direction and asecond pixel driving circuit of the second driving circuit groupadjacent to each other is greater than a distance between two firstpixel driving circuits of the N first pixel driving circuits included inthe respective first driving circuit groups and adjacent to each otherin the second direction and a distance between two second pixel drivingcircuits of the N second pixel driving circuits included in therespective second driving circuit groups and adjacent to each other inthe second direction.
 8. The display device of claim 6, wherein thedriving layer further comprises signal lines, wherein a predeterminednumber of the signal lines has a bent shape in the vacant area.
 9. Thedisplay device of claim 8, wherein a predetermined number of the signallines is branched in the vacant area to be electrically connected to theN first pixel driving circuits and the photo driving circuit.
 10. Thedisplay device of claim 1, wherein the photo sensor comprises: a lowermetal layer disposed on the substrate; an active layer disposed on thelower metal layer; an upper metal layer which is disposed on the activelayer and in which an opening exposing a portion of the active layer isdefined; an absorption filter which is disposed on the upper metal layerand covers the opening; and an interference filter which is disposed onthe upper metal layer and covers the opening.
 11. The display device ofclaim 1, wherein the display element layer comprises: a pixel definitionfilm which overlaps the photo sensor; and a lens which overlaps thephoto sensor on the pixel definition film and includes a same materialas that of the pixel definition film.
 12. The display device of claim 1,wherein a display area where an image is displayed and a non-displayarea adjacent to the display area are defined on the display device,wherein the non-display area comprises a first bending area definedoutside a first side of the display area in the first direction, a firstpad area defined outside the first bending area in the first direction,a second bending area defined outside a second side of the display areain the second direction, and a second pad area defined outside thesecond bending area in the first direction, wherein the substrate isbent along a bending axis extending in the second direction intersectingthe first direction in the first and second bending areas, furthercomprising: a first driving circuit chip which provides a signal to theN first pixel driving circuits and the photo driving circuit and isdisposed on the first pad area; and a second driving circuit chip whichreceives a signal sensed by the photo pixel and is disposed in thesecond pad area.
 13. The display device of claim 12, further comprisinga flexible printed circuit substrate which connects the first pad areaand the second pad area of the display device to each other.
 14. Adisplay device comprising: a substrate; a driving layer disposed on thesubstrate, and comprising first driving circuit groups each comprising aplurality of first pixel driving circuits and photo pixels and seconddriving circuit groups each comprising a plurality of second pixeldriving circuits, wherein the first driving circuit groups and thesecond driving circuit groups are spaced apart from each other in afirst direction; and a display element layer disposed on the drivinglayer, and comprising a plurality of first display elements electricallyconnected to the plurality of first pixel driving circuits through aplurality of first contact holes, respectively, and a plurality ofsecond display elements electrically connected to the plurality ofsecond pixel driving circuits through a plurality of second contactholes, respectively, wherein a minimum distance measured in a firstpredetermined direction between first color display elements included inthe plurality of display elements in a plan view and a minimum distancemeasured in a second predetermined direction orthogonal to the firstpredetermined direction between first color display elements included inthe plurality of first display elements in the plan view aresubstantially the same, wherein a first driving circuit group among thefirst driving circuit groups and a second driving circuit group amongthe second driving circuit groups adjacent to the first driving circuitgroup in a second direction different from the first direction arespaced apart from each other, and wherein a distance between adjacentfirst contact holes of the plurality of first contact holes respectivelycorresponding to directly adjacent first pixel driving circuits of the Nfirst pixel driving circuits is smaller than a distance between adjacentsecond contact holes of the plurality of second contact holesrespectively corresponding to directly adjacent second pixel drivingcircuits of the N second pixel driving circuits, in the seconddirection.
 15. The display device of claim 14, wherein a distancebetween a first pixel driving circuit of the first driving circuit groupadjacent to each other in the first direction and a second pixel drivingcircuit of the second driving circuit group is greater than a distancebetween two first pixel driving circuits of the plurality of first pixeldriving circuits included in the respective first driving circuit groupsand adjacent to each other in the first direction and a distance betweentwo second pixel driving circuits of the plurality of second pixeldriving circuits included in the respective second driving circuitgroups and adjacent to each other in the first direction.